We are heading into our third season of winter in our straw bale house. Hard to believe really – I so clearly remember the feeling that the house would just never be done – but there you have it, two years later we are really beginning to see the way the design and materials of the house perform through the seasons. Last winter was a relatively mild winter in an already mild climate zone, and the winter before we didn’t really move in fully until January, so getting a sense of how much wood we might burn and how much our heating/electrical costs would be throughout the winter months has only just begun to be obvious.

winter sun bouncing off the pond

Our three forms of heat are the wood stove, hydronic in-floor heating, and passive solar orientation. The winter sun arches across the sky, sending it’s light and heat into our east and south windows (when it is out!) staying entirely above the top of the trees of the ridge across the valley of which we face. At certain times of the spring and fall, the light of the sun bounces off the pond below us which lights up our ceiling with ripply light- an unplanned bonus! We have an earthen floor in the front room, which noticeably absorbs the warmth and retains it into the evening. The wood stove sits on a two foot tall stone hearth and is backed by a short cob wall, both of which absorb sun heat as well as stove heat.

In floor heating tubes covered by 3 inches of cob sub floor mass

Our in-floor heating is divided into two zones, one for the bathroom and north side of the house, and one which circulates the front south room. They are set to come on if the temperatures of the rooms drop below 19 degrees celsius. The front room heating has never come on, and the backroom zone clicks on early in the mornings of the coldest days of winter. The tubes are embedded under 3 inches of cob, which then also retains heat for longer.

We primarily rely on the wood stove for immediate heat. This year we lit our first fire on November 20th, and mostly because we were nostalgic for that first cozy fire. We kept the fire going for about an hour, and then we were too hot. We have found that we really only need to light a fire around four or five o’clock, depending on the temperature outside, and let it die down around nine, otherwise it gets up to 25 degrees! We have been having a cold spell right now, where temperatures fall towards -2 or -3 degrees at night (oh my!), and then we might light a fire at three in the afternoon. Our evening fires keep the house sitting at 20 until late the next day. Last year, this translated into our using less than half a cord of fire wood in the whole season. We have an older style stove that doesn’t have any of the newer reburning/efficient innovations, and our space is 920 interior square feet.

The southerly exposed room of the house is lowered by two steps, (which is where the wood stove is) and so the heat tends to naturally move towards the north side of the house as it attempts to travel upwards. If we leave one window open in the loft of the back room, the heat is pulled even more into that space. Another design feature of the walls themselves are the wrap- around construction – meaning that the bales are continuously wrapped around the outside of the timber frame, leaving no thermal breaks except where there are doors and windows. We used double pane thermal glass with argon gas and a low-E squared coating.

south and west side- wrapping bales, sun exposure, and roof overhang

I love the heat that a wood stove gives, but I am not excited about the amount of wood and trees that need to be burned. It is not entirely a “clean” way of heating. Eventually we will have three wood stoves on our property – this one, one in the work shop, and one in our addition to this house. Luckily, Colin’s business of crafting furniture from salvaged red cedar means that we have a lot of great kindling and fire wood just from his waste. I am comforted to know that we can potentially heat our spaces for years on just a few dead or cleared trees. We took out a few trees when building the house, and haven’t even started using them. This fall, I chopped almost two cords of wood from those trees, which will potentially be three years of wood. The less wood we go through the better – we even find that turning on the stove to make dinner warms the space efficiently some nights. Certainly, if we have friends over in the evening, lighting a fire usually leads to opening some windows.

Straw bales reportedly have an R value of 30-60. The building code requires that insulation needs to have an R value of 20 in walls. We have experienced this amazingly efficient quality of insulation, in the winter and in the summer, when the inside of the house is cool and refreshing on hot days. With a 3 foot overhang of the roof blocking out the sun’s light in summer and the rain in the winter, I am ever more convinced that straw bales are a fantastic way of providing natural temperature control in any climate.

Share this:

Like this:

Related

Hello… Lovely blog!
I am very inspired about the way you live and how you build a house.
I did not notice your house plans. Have you posted it anywhere?
How many rooms is in the house…?
I’m interested because i have a desire to build a similare house.

Hi Martin,
our house so far is really just 2 big rooms, very open plan. One is a 600sqft in-law suite for my mother in the long run, and other part is a 300sqft art studio shared between all of us (mother is a painter/print maker, and I do fibre arts, weaving, felting..) the only closed rooms are the bathroom and utility room. So for now we are sleeping in the suite, mother is in the art studio and the kids in the loft above the art studio. We will be adding on another 1000sqft in the near future, which will have 2 bedrooms for the kids, a master bedroom for us, bathroom, and second kitchen/living room area. We hope to start on that in the next year. Hope this helps you out!

Hi Thanks for the earlier response about where you sourced the bales. I have contacted Michells. Another question if you don’t mind. What system have you used for your hydronics? Immersion boiler, heat pump, solar hot water, a combination? My research has left me entirely unclear on the best system for our [pending] hydronics. Many thanks! Rob

Rob, Wendi’s husband Colin here.. So I put in the smallest tankless electric boiler I could get (which is a 6kw Ergo) to use for heating the water in the floor. It works very well, only comes on when needed and is very efficient at what it does. I plan on adding solar hot water panels (evacuated tubes) in the future and using the solar hot water as a preheat for the floor in the winter and for heating most of my domestic water three quarters of the year. From the research I have done for our climate I am going to go with a drain back system using water instead of glycol. This uses a small tank up high above a storage tank (which could also double as the electric backup) and that way no water is left in the panels overnight or when the weather is very cold. My neighbour has a small prefab system that has a storage tank attached to it right on the roof with the tubes, it was cheap and works well most of the year, but does not provide freezing protection so it must be emptied for 3-4 months over the winter, but it does provide most of their hot water in the summer and shoulder seasons. A good affordable option. I will also be using our pond as a heat sink with a heat pump do heat water for the second half of the house in the future…. lots to think about! Best of luck with your project, and feel free to call or visit if ever on Pender. Colin.

Many thanks for this information. My designer here on Gabriola also uses a tankless on-demand system tied in with her evacuated tube solar hot water system.

My thinking is now heading in the direction of using a conventional immersion boiler, because they are cheap, and then putting the money I save over solar hot water or a heat pump into a solar PV array. I reckon that if we can control our demand side and design our energy use to be half of the BC average or around the average UK or German resident [I just came back from 10 years in the UK so I have an idea of what this means] then a 6Kw system, grid-tied, which might cost about $8500, might on average generate all of our electricity for a year, including the immersion boiler. A new Gabe Solar group has started up on Gabriola with the goal of buying PV systems at wholesale prices, much like Sustainable Gabriola does for heat pumps. So PV as a substitute for solar hot water is my current thinking. I’m not sure exactly what the calculations will show [maybe I am wrong] and we might go a year to see what our Hydro bills are before installing the most beneficial system. I have some friends in New Zealand who built the http://www.zeroenergyhouse.co.nz [watch their short videos, they are great]. They will be visiting us in May for a week and they are both PV and building engineers so I will be running my options by them in order to figure out the best way forward.

I appreciate the offer of a visit and definitely will take you up on it at some point. We are awaiting our plans from the engineer and then the mad rush begins to get a roof up and the building sealed before the winter rains [he says as it is bucketing down right now]. We are doing a roundwood frame of site cut trees, 18 inch light clay straw on the ground floor and 12 inches of blown in cellulose upstairs. Lime / clay plaster finishes inside and out, cob floors with hydronics. The goal is R66 in the roof, R30 under the cob slab, R30 slip straw walls with medium high thermal mass and R45 walls upstairs with triple glazed fibreglass windows all around. We are aiming to do this on a tight budget, perhaps too tight, but the ongoing low operating costs and high aesthetic and comfort values will make it worth it. Your pond idea is intriguing. We are digging a pond for irrigation so this might be worth considering.

If you ever come to Gabriola please come for a visit and see our project. If I ever get a moment without the hammer in one hand and the toddler in the other I’ll get our blog site up so you can see the [slow] progress.